Scientific Papers Series A. Agronomy

an 11.6% mass loss and a 145.5 J/g process
enthalpy. In the temperature range of
267-600°C the mass loss was 5.4%, when a
slight exothermal effect could be noticed, with
a 58.3 J/g enthalpy, the maximum heat
eliminated being of 419.8°C for a heat flow of
1.12 mW. The fourth decomposition state took
place in the temperature range of 600-800°C
with a 4.7% mass loss. The humic/fulvic mix
present in the fertilizer matrix contained about
70% organic acids, whereof 50% derive from
humic acids and 20% from fulvic acids. The
spectral analysis of the humic substances was
made by Fourier transform infrared
spectroscopy (FTIR) by means of the
PerkinElmer Spectrum 100 and the VERTEX
70 spectrometers respectively, in the wave
length range of 650-4000 cm 1 (Figure 2).
Figure 2. FTIR image of the humic acid extracted from
the coal mass (lignite) (according to Pârvan et al., 2012)
Table 1. Composition of the AH-type fertilizers
AH FERTILIZERS
Composition
AH - I (g/l) AH - U (g/l) AH - N (g/l)
Humic acids 20.5 20.5 15.5
Total nitrogen (N) 90 55 165
Phosphorus (P 2 O 5 ) 35 50 30
Potassium (K 2 O) 35 50 30
Boron 0.2 0.15 0.18
Cobalt 0.005 0.005 -
Copper 0.1 0.15 0.2
Iron 0.25 0.3 0.4
Magnesium 0.1 0.15 0.4
Manganese 0.15 0.2 0.4
Molybdenum 0.005 0.005 -
SO 3 0.5 0.5 15
Zinc 0.1 0.15 0.2
EDTA 2.8 2.8 8.5
Total s.a 184.71 179.91 265.78
All the spectra were obtained by total infrared
reflection with the ATR (Attenuated Total
Reflectance) module. The resolution was
4 cm -1 , with the average of 4 up to 32 scans and
the correction of the CO 2 and H 2 O fund, in the
transmittance mode.
Table 1 presents the physical - chemical
characteristics determined for the fertilizers
with humic acids obtained experimentally -
AH-U, AH-N, AH-I, KH.
RESULTS AND DISCUSSIONS
Effects of the treatment with humate-based
liquid fertilizers on the soil in the corn crop
In the first year of the experiment it was found
that the application of one dose (100 l/ha) of
the new fertilizer AH-I resulted in the reduction
of the mobile potassium content in the soil as
compared to the non-fertilized control. The
values recorded were 144 mg/kg as compared
to 170 mg/kg. Increase of the dose of humatebased
liquid fertilizer to 150 l/ha resulted in the
significant reduction of the K AL in the soil, the
value of the mobile potassium in the soil
dropping to 120 mg/kg as compared to the
value of the non-fertilized control, i.e.
170 mg/kg due to the fertilizer containing NPK
in its matrix. By the application of the AH-U
liquid fertilizer in two doses, the contents of
mobile potassium in the soil increased
significantly to 188 mg/kg as compared to the
non-fertilized control of 170 mg/kg. Potassium
humate applied in a 100 l/ha dose reduced
significantly the K AL content in the soil to
140 mg/kg as compared to the non-fertilized
control of 170 mg/kg.
In the second year of the experiment on the slag
heap the effects of the treatments with humatebased
liquid fertilizers were noticeable by the
drop of the mobile phosphorus in the soil as
compared to the non-fertilized control. The
potassium humate applied in one dose
(100 l/ha) reduced the mobile phosphorus
contents in the soil to the value of 46.72 mg/kg
as compared to the non-fertilized control whose
value was 47.95 mg/kg. As for mobile
potassium, the application of the liquid
fertilizers resulted in obvious increase
following the application of the liquid fertilizer
AH-I in two doses (150 l/ha): 199.20 mg/ha as
compared to the non-fertilized control, 186
mg/kg, due to the fertilizer containing NPK in
its matrix.
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